Magnetic Exoplanets in the Subalvenic Stellar Wind: Collimators of the Interplanetary Magnetic Field

Many exoplanets have been discovered very close to their parent stars. The radius of their orbits relative to the Alfvén radius and the characteristics of the parent star determine the mode of flow of the stellar wind around these planets: sub-Alfvénic or super-Alfvénic. The distance from the center of the star at which the kinetic and magnetic energy densities are equal is called the Alfvén radius. If a magnetic exoplanet is located beyond this distance, a comet-like magnetosphere with a bow shock in front of it forms around it. If the exoplanet is located inside the Alfvén radius, the magnetosphere turns into Alfvén wings. Here we will consider how the transition from a comet-like magnetosphere to Alfvén wings occurs due to the growth of the magnetic field of the stellar wind with the most efficient orientation for reconnection and how, due to this process, the bundle of open field lines in interplanetary space is transformed, compressed into a narrow tube.